Conceptual design of subcritical assembly for NPP nuclear waste transmutation study based on Kartini reactor

The conceptual design theoretical study and technical feasibility analysis results of subcritical assembly (Small Scale Reactor Accelerator Driven System /SS-RADS) based on Kartini reactor is presented in this paper. The reactor core model is a cylindrical containing minor actinide (MA) surrounded by Kartini reactor fuels. ADS-CDS module based on SRAC code was used to study neutronic aspect. Calculation results show that the present of MA as nuclear waste will provide positive reactivity value and will increasing according to its concentration. The ORIGEN2 computer code was used to calculate MA transmutation as a function of neutron energy and flux. The analysis results show that the optimum waste transmutation of the above radionuclide will achieved with thermal neutron (thermal reactor), instead of fast neutron. The most transmuted element is Am²⁴¹ with 50% transmutation rate at thermal neutron flux of 1,013 n/cm²s, the lowest transmuted is Cm²⁴⁴ i.e. only 0.5%, and total average transmutation is 32%. It can be concluded that the SS-RADS based on Kartini reactor can be used for nuclear waste transmutation study if the thermal neutron flux level is around 1,013 n/cm²s. (author)